A computer information storage library (also known as an autochanger) typically includes at least one computer information drive mechanism, a media storage system for computer information media or data cartridges, a picker (also called a gripper or manipulator or engagement mechanism) for inserting media or cartridges into drives or storage locations and for extracting media or cartridges from drives or storage locations, and a transport mechanism for moving the picker and media or cartridges between drives and storage. Computer information storage drives with removable media include, for example, disk drives (magnetic and optical) and magnetic tape drives.
Media storage systems include, for example, carousels, cylindrical silos, and slotted magazines or racks. There is a wide spectrum of transport assemblies. For example, cartridges may be translated and rotated with four or more degrees of freedom by an anthropomorphic robot arm or cartridges may simply be translated in two dimensions. Alternatively, instead of a separate transport mechanism, the media storage system may be moveable. For example, a carousel may rotate to position a cartridge at a stationary drive.
Alternatively, a drive may be moved by a transport system to a stationary cartridge location. There is also a wide spectrum of pickers. For example, friction grippers with multiple fingers may be used, various media or cartridge features may be hooked or clamped, or cartridges may be simply pushed or pulled. In particular, the DLT tape cartridge, commercially available from Quantum Corporation, Milpitas, Calif., is of interest for computer information storage libraries. DLT tape cartridges are also available from ATL Odetics and Overland Data, besides Quantum.
A computer information storage library or autochanger generally has a storage rack for holding a plurality of media cartridges that are not currently being retrieved or otherwise utilized by the autochanger in a storage location. Generally, a robotic arm or picker will retrieve a media cartridge from its location in the storage rack and place it in a drive when the particular media cartridge is needed. The media cartridge will generally be returned to the same or a different location on the storage rack when it is no longer being used. Media cartridges are held in both fixed (i.e., nonremovable) and removable storage slots or caddies on the storage rack. Removable caddies may hold about five cartridges, although five is not a magical number and a caddy may accommodate a different number of data cartridges. The storage caddies can be removed from the storage rack and changed out for a different storage caddy of media cartridges.